Tire Size Box

225/35R17 vs 225/40R17

225/40R17 compared with 225/35R17

+3.8% diameter, 0.0" width

225/40R17 is 24.09" tall vs 23.20". More than the 3% rule of thumb, so check carefully before switching.

23.2"17" rim3.1"8.9" wide
225/35R17 (solid) compared with 225/40R17 (dashed outline), drawn to scale

With 225/40R17 tires, when your speedometer says 60 mph you are really going

62.3 mph

225/40R17 is +0.89 inches (+3.8%) in overall diameter. That is more than the 3% most shops and makers recommend.

225/35R17225/40R17Difference%
Overall diameter23.20"24.09"+0.89"+3.8%
Section width8.86"8.86"0.00"0.0%
Sidewall height3.10"3.54"+0.44"+14.3%
Circumference72.89"75.67"+2.78"+3.8%
Revolutions per mile869.3837.3−32.0−3.7%

Speedometer difference

If your vehicle came with 225/35R17 and you fit 225/40R17, here is your real speed for each speedometer reading:

Speedometer showsActual speedDifference
20 mph20.8 mph+0.8 mph
30 mph31.1 mph+1.1 mph
40 mph41.5 mph+1.5 mph
50 mph51.9 mph+1.9 mph
60 mph62.3 mph+2.3 mph
65 mph67.5 mph+2.5 mph
70 mph72.7 mph+2.7 mph
75 mph77.9 mph+2.9 mph
80 mph83.1 mph+3.1 mph

Each size on its own

Questions

Which is bigger, 225/35R17 or 225/40R17?
225/40R17 is taller by 0.89 inches (24.09" vs 23.20"). 225/35R17 is the same width.
Can I replace 225/35R17 with 225/40R17?
It is not recommended without checking carefully. The diameter difference is +3.8%, more than the 3% most shops and makers allow. It will throw off the speedometer and may affect ABS, stability control and clearance.
How much will 225/40R17 change my speedometer?
When your speedometer reads 60 mph with 225/40R17 fitted (calibrated for 225/35R17), your real speed is 62.3 mph. Your odometer will under-count miles by about 3.8%.
Will 225/40R17 lift my vehicle?
Ride height changes by half the diameter difference: +0.44 inches of ground clearance at the axle.

Other comparisons